A breech of a repeating rifle of this type is known from DE 43 05 700 C1. In that document, a bolt head and a locking sleeve arranged concentrically about this bolt head are arranged within a locking guide that is displaceable on a receiver. The locking sleeve constructed as an expansion sleeve is divided at its front end into several flexible spring tongues by longitudinal slots. The spring tongues have locking elements at their front ends for engaging in an annular groove on the inside of the barrel. By means of an expansion cone provided on the bolt head, the locking elements constructed integrally with the spring tongues of the locking sleeve can move between a radially inner unlocked position and a radially outer locked position. For this known breech, the advance of the lock guide that is displaceably arranged on a receiver is controlled by an individual cam element arranged so that it can rotate in the lock guide.